A changing climate - Urgent need for action
In a report released in Yokohama, the panel* - the international body for assessing the science related to climate change - says the risks to the Earth's ecosystems are considerable and will be difficult to manage with high levels of global warming.
The report, Climate Change 2014: Impacts, adaptation and vulnerability was prepared by the IPCC's Working Group II as a contribution to its Fifth Assessment Report.
Panel members, consisting of government delegates assisted by a team of scientists, opened a five-day meeting last week in Japan to finalise details of the report.
The meeting was the culmination of four years of work by hundreds of experts who have volunteered their time and expertise to produce a comprehensive assessment of the global effects of the Earth's changing climate.
In all, 309 coordinating lead authors and review editors, drawn from 70 countries, were selected to produce the report. They enlisted the help of 436 contributing authors and a total of 1,729 expert and government reviewers.
But if past reactions are any guide, this latest document will also generate controversy and disputes over its findings.
The report concludes that responding to climate change involves making choices about risks in a transforming world. It says the nature of the risks of climate change is increasingly clear although climate change "will also continue to produce surprises".
Need for action
In identifying vulnerable people, industries and ecosystems around the world, the expert group says the big risk from a changing climate comes from a lack of preparedness and exposure of people or assets to harm, overlapping with triggering climate events or trends.
"Each of these three components can be a target for smart actions to decrease risk. We live in an era of man-made climate change," said Vicente Barros from the University of Buenos Aires in Argentina, who co-chaired the group with Chris Field of the US Carnegie Institution for Science and Stanford University.
"In many cases, we are not prepared for the climate-related risks that we already face. Investments in better preparation can pay dividends both for the present and for the future," Barros said.
Field said that adaptation to reduce the risks from a changing climate was now starting to occur, but with a stronger focus on reacting to past events than on preparing for a changing future.
"Climate-change adaptation is not an exotic agenda that has never been tried. Governments, firms and communities around the world are building experience with adaptation," he said.
"This experience forms a starting point for bolder, more ambitious adaptations that will be important as climate and society continue to change."
The latest report follows one released last September and will be followed by a third in April. The IPCC Fifth Assessment Report cycle concludes with release of its Synthesis Report in October.
The current report consists of two volumes: the first contains a summary for policy-makers, a technical summary, and 20 chapters assessing risks by sector and opportunities for response.
The sectors include freshwater resources, terrestrial and ocean ecosystems, coasts, food, urban and rural areas, energy and industry, human health and security, and livelihoods and poverty.
A second volume of 10 chapters assesses risks and opportunities for response by region. These include Africa, Europe, Asia, Australasia, North America, Central and South America, the polar regions, small islands and the ocean.
An international team prepared a 2,000-page assessment based on more than 12,000 scientific papers and other documents. The subsequent report was then subject to several rounds of review, resulting in tens of thousands of comments that were addressed one by one.
Last week, government delegates went through the summary for policy-makers line by line, proposing changes to make it sharper, while the author team tried to ensure the summary remained consistent with the underlying chapters.
The report says observed impacts of climate change have already affected agriculture, human health, ecosystems on land and in the oceans, water supplies, and some people's livelihoods.
The striking feature of observed impacts is that they are occurring from the tropics to the poles, from small islands to large continents, and from the wealthiest countries to the poorest.
It concludes that people, societies and ecosystems are vulnerable around the world, but with different vulnerability in different places. Climate change often interacts with other stresses to increase risk, it says.
Decreasing risks through adaptation
Adaptation can play a key role in decreasing these risks.
Part of the reason adaptation is so important is that the world faces a host of risks from climate change already baked into the climate system, due to past emissions and existing infrastructure, the report states.
Understanding that climate change is a challenge in managing risks opens a wide range of opportunities for integrating adaptation with economic and social development, and with initiatives to limit future warming, the report says.
"We definitely face challenges, but understanding those challenges and tackling them creatively can make climate change adaptation an important way to help build a more vibrant world in the near-term and beyond," it says.
Rajendra Pachauri, chair of the IPCC, said the report was another important step forward in understanding how to reduce and manage the risks of climate change.
Along with the previous and the next report, he said these would provide "a conceptual map of not only the essential features of the climate challenge but the options for solutions".
"The IPCC's reports are some of the most ambitious scientific undertakings in human history, and I am humbled by and grateful for the contributions of everyone who makes them possible."
* The Intergovernmental Panel on Climate Change was set up in 1988 by the World Meteorological Organization and the United Nations Environment Programme to provide policy-makers with regular assessments of the scientific basis of climate change, its impacts and future risks, and options for adaptation and mitigation.
Pachauri has headed the panel since 2002 and it was during his tenure that the committee was collectively awarded the Nobel Peace Prize in 2007.
The Fifth Assessment Report is the result of the work of 837 coordinating lead authors, lead authors, and review editors.